Electric vehicles including in-wheel motor driving devices, and electric vehicles including independent steering apparatuses implemented by steering-by-wire system are both already public (Patent Literature 1 and 2).
The in-wheel motor driving device includes a motor section which generates a driving force; a speed reducer section which reduces rotating speed of the motor section and outputs the rotating force; and a wheel hub which transmits the output from the speed reducer section to a driving wheel. The speed reducer section is provided by a planetary gear system for example. An onboard motor controller provides electronic control on rotation speed, rotation direction, etc. of the in-wheel motor driving devices (Patent Literature 1 and 2).
The independent-steering apparatus implemented by steering-by-wire system uses a steering actuator installed in each vehicle wheels. The apparatus includes a steering angle controller which, in response to the vehicle driver's operation on the steering wheel, calculates target steering angles and provides electronic control on the steering actuators thereby setting the wheels to appropriate steering angles (Patent Literature 3).
An electric vehicle equipped with the independent steering apparatus can make pivot turning, i.e., turning on the spot, by placing the front wheels in a forwardly narrowing pattern, placing the rear wheels in a rearwardly narrowing pattern, and then, if the vehicle is a two-wheel drive type, by rotating the left and the right driving wheels in the front or rear of the vehicle in mutually opposite directions. In a four-wheel drive vehicle, the left and the right wheels are rotated in mutually opposite directions in both of the front and rear pairs, with the front and the rear left wheels rotated in the same direction while the front and the rear right wheels rotated in the same direction. Such a control provides pivot turning.